My dream in WoW is to have several toons at max level professions so I can make money and not rely on the auction house. To do this I need to get more toons to 90. I have played a mage for years and that is what I am good at. I would like to try different toons. I know there are addons that help with rotations. Which is the best one?

I really dislike it when people use rotation helpers. It's not that difficult to learn your rotation, and you will play better if you understand your rotation and can adapt. That said, there are a number of crutch addons out there. Off the top of my head:

Ret Paladin - CLCRet

Frost DK - CLCDK

Feral Druid - Claw

Elemental Shaman - Elementarist

There is also Ovale which works for all classes, and can be further customized with custom scripts that can be found on class specific forums.

Instead of using addons that tell you your rotation, you're better off using addons that show you the information you need to make better spell choices. I highly recommend using Weak Auras to track your buffs, debuffs, cooldowns, and pretty much anything you can think of.

Rotation helpers are a crutch, and they do make you look a bit like a noob when you use one. You'll enjoy a class a lot more when you can understand its intricacies and excel at it. Just my two cents.

As training wheels I understand, and it's fine, but a lot of people actually use these addons for raiding. My friend linked me a stream of some Eleshaman who was working on H-Juggernaut, telling me that "this guy is sick, he does such good damage." I opened the stream and Elementarist displayed prominently in the middle of his screen. I mentally facepalmed and closed it.

Go to http://www.icy-veins.com and check out each class and specialization's rotation. There are also many resources like what talents to build for questing, PvE, PvP, etc. and also enchant, gems, and reforming guides.

I love icy-veins guides. They give a quick priority list you can get started with, but then they go into a lot of detail of why it's the best. They essentially guide you from knowing nothing to the ins and outs of your spec and you can stop whenever you're comfortable along the way.

Most addons as described are usually class specific. I'm not sure of an addon that helps you with your rotation for every class in one, but I know Noxxic.com has some pretty good explainations of each classes rotation @ 90.

Pretty much all "rotations" have become priority-based skill usage now. In other words, you're not memorizing a set order and timing for your abilities, you are remembering the priority in which you need to cast each ability as it comes off cooldown/becomes available and reacting to different buffs/procs as they occur.

Most procs already have a bright visual indicator when they occur (Fingers of Frost does, the "free Pryo" thing for Fire mages does, Arcane Missles does), so no addon should be necessary there.

For buffs, there are addons such as TidyPlates, XPerl, and ElvUI that can make it easier to track/maintain/react to buffs and debuffs.